If he did not renaturalize on his return to Hawaii, but kept his Indonesian papers and passports, he'd have a hard time selling anyone that he was still NBC. I think that that is his real issue -- he used his Indonesian passports beyond age 21 and applied as an Indonesian citizen for certain collegiate benefits. If he did that, I think he has legal as well as political problems.
His adoption would not cause any NBC difficulties, I've been assured here in FR, as long as he renaturalized timely on his return from Indonesia. His father, I was told, could not alienate him as a minor on the father's own motion, as long as Barry renaturalized on his return. (And it isn't certain that he did -- his family were Reds and Bohemians, after all. His mother apparently kept her married name -- spelt "Sutoro" by her -- and her Indonesian citizenship until her death.)
My belief is that unless he renounced his citizenship as an adult nothing else matters and there is no need to “renaturalize” since acts as a minor are not legally binding.
I also believe that his school records would be embarrassing and fraudulent as well as being part of this citizenship problem.
But NONE of this changes the fact that his father was NOT an American citizen (if his own words are true) and therefore, Urkel cannot be a NBC.